Heavy Metal Adsorption by Biochar Made from Longan Seeds and Peels

Abstract

This work aimed to study the adsorption of lead and arsenic with biochar made from longan seeds and peels. The longan seeds and peels were pyrolyzed at 300ºC for 4 h with a heating rate of 5ºC/min. Then, the biochar was dehumidified in the hot air oven at 105ºC for 24 h and put in the desiccant jar for 24 h. The solution of 100 ml was prepared using 50 g of fertilizer, mixed with 100 ml of DI water and shaken for 30 min at 200 rpm. The 0.4 g of biochar was added to the solution and shaken for 0.5, 1, 2, 4, 6, 8, 12, and 24 h at 200 rpm. The solution was then filtered and was examined by X-ray fluorescence. The results showed that the arsenic adsorption of the biochar from longan peels at shaking times of 0.5-2 and 4-24 h were 14.33±3 ppm and 6.8±4.23 ppm, respectively, while the biochar derived from longan seeds did not adsorb arsenic at a shaking time of 0.5-24 h with the arsenic concentrations of 4.78±3.56 ppm. The lead adsorption of the biochar derived from longan peels was not significantly different for shaking time of 0.5-24 h, which was 4.48±3.27 ppm. However, lead adsorption in the biochar from longan peels was higher than that in the biochar derived from longan seeds for the same shaking period. According to the study, it could be used as a guideline for investigating the adsorption of heavy metals with the biochar made from longan seeds and peels.